It depends on the WordPress theme you’re using. If you can find out what html class the category/post meta is under using Inspect Element, it will be easy to hide it via CSS. Otherwise you will need to find where the ‘Post Meta Data’ is being added in PHP inside your theme and remove it.
For now you can try and paste the following code inside your style.css file and see if it works, but it’s just guessing at this stage:
footer.entry-footer, .entry-meta {
display: none;
}